Red Hat Bugzilla – Bug 1261946
Neutron traceback when an external network without IPv6 subnet is attached to an HA Router.
Last modified: 2016-04-26 14:53:36 EDT
Description of problem:
For an HA Router which does not have any subnets in the external network, Neutron
sets the IPv6 proc entry on the gateway interface to receive Router Advts from
external IPv6 router and configure a default route pointing to the LLA of the external IPv6 Router.
Normally for an HA Router in the backup state, Neutron removes Link Local Address (LLA)
from the gateway interface.
In Kernel version 3.10 (used in platforms like RHEL7/Centos7) when the last IPv6 address is removed from the interface,
IPv6 is shutdown on the iface and the proc entries corresponding to the iface are deleted (i.e., /proc/sys/net/ipv6/conf/<interface>)
This issue is resolved in the later kernels , but the issue exists on platforms with Kernel version 3.10
When IPv6 proc entries are missing and Neutron tries to configure the proc entry we see the following traceback in Neutron.
Command: ['ip', 'netns', 'exec', 'qrouter-e66b99aa-e840-4a13-9311-6242710a5452', 'sysctl', '-w', 'net.ipv6.conf.qg-1fc4061d-3c.accept_ra=2']
Exit code: 255
Stderr: sysctl: cannot stat /proc/sys/net/ipv6/conf/qg-1fc4061d-3c/accept_ra: No such file or directory
Version-Release number of selected component (if applicable):
Steps to Reproduce:
1. Create an HA Router
2. Create an internal network, subnet and associate the internal subnet to HA router.
3. Create an external network without any subnet.
4. Associate the external network with the HA Router.
5. Do not configure "ipv6_gateway" in neutron l3_agent.ini configuration.
Traceback seen in Neutron l3-agent logs.
Neutron should not trace out.
The patch got into 2015.1.1 thru rebase. It's not a regression though since HA routers never worked with IPv6 external networks with no subnets before.
It affects functional test CI for OSP, so we may need to revert the patch before proper fix emerges.
*** This bug has been marked as a duplicate of bug 1262647 ***